Opal, Wyoming has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 24.8 °F (low) to 54.8 °F (high). Annual precipitation averages 8.9 Inches. Opal is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.6 °F | 30.1 °F | 0.52 in. |
| February | 6.7 °F | 32.4 °F | 0.49 in. |
| March | 16.8 °F | 42.6 °F | 0.62 in. |
| April | 24.2 °F | 52.4 °F | 0.86 in. |
| May | 32.6 °F | 62.4 °F | 1.43 in. |
| June | 39.4 °F | 73.4 °F | 0.89 in. |
| July | 45.9 °F | 82.5 °F | 0.56 in. |
| August | 44.0 °F | 81.0 °F | 0.76 in. |
| September | 35.5 °F | 71.5 °F | 0.95 in. |
| October | 25.8 °F | 57.3 °F | 0.81 in. |
| November | 15.6 °F | 41.8 °F | 0.51 in. |
| December | 5.9 °F | 30.5 °F | 0.51 in. |
| Annual | 24.8 °F | 54.8 °F | 8.91 in. |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |